No-tillage planting is a new sowing technique that sows directly on a soil surface which is covered by straw or stubble and free from ploughing in advance. As the no-tillage soil surface is relatively firm and covered by straw, usually there is a ploughing component or mechanism installed on a sowing element of a no-tillage planting machine. The ploughing component or mechanism can loosen the seedbed soil in strips, so that suitable ploughed conditions can be provided for following ditching, soil-covering and suppressing. Therefore, the ploughing component or mechanism is one of key parts for the no-tillage planting machine. To better perform no-tillage planting, the ploughing mechanism of the no-tillage planting machine should possess good performance in soil entering, stubble cutting and soil strip loosening and crushing.
Currently, soil treating mechanisms having a soil crushing function of existing agricultural machinery may be divided into an active rotation type and a passive rotation type. The active rotation type is mainly used in primary tillage equipment and scarification equipment, such as rotary blades (disclosed in the Chinese patent No. ZL201210138776.0) and stubble cutting blades (disclosed in the Chinese patent No. ZL200620077979.3). Such machinery treats a large amount of soil and the structures of ploughing layers are greatly destroyed, so it is not suitable for the no-tillage planting work. The passive-type soil crushing rollers (disclosed in the Chinese patent No. ZL201310000902.0), generally suitable for soil tillage and scarification machinery, are used to further crush the ploughed soil and do not have the soil loosening function. Therefore, such machinery is usually independently used and cannot co-operate with the no-tillage planting machine.
International mainstream no-tillage planting machines usually employ wavy disc coulter (disclosed in the Chinese patent No. ZL201010004737.2) as soil loosening members. Wavy disc coulter may be divided into wide wavy disc coulters and narrow wavy disc coulters according to the ploughing width. The wide wavy disc coulter has relatively large wrinkles which are stuck with much more seedbed soil when ploughing sticky and heavy soil. When working at high speeds, such coulters greatly destroy the structure of the ploughing layers, resulting in the sowing depth is non-uniform and seeds cannot properly contact with the soil, thereby affecting the emergence rate. The narrow wavy disc coulters have a relatively small range of corrugations, so the soil entering performance is good, and it throws less seedbed soil than the wide wavy disc coulter do. However, its soil loosening width is small, and the soil loosening effect is poor. Therefore, the narrow wavy disc coulters cannot provide good conditions for the followed sowing.
Both the wide and narrow wavy disc coulter can only work in certain conditions. In addition, owing to their specific structures, wavy disc coulters can only loosen rather than crush the soil. Loosened soil blocks can easily form air cavities, so that sufficient contact between the soil and seeds cannot be provided, and moisture in the seedbed evaporates easily, affecting sprouting of seeds.